Patent GB-1044206-A (GB)
Title: Pressure compensated directional control valve
Inventor: LEE JOHN CHIA-CHIN
IPC: F15B13/01
Filed: 1963-08-01
Abstract: 1,044,206. Valves. BORG-WARNER CORPORATION. Aug. 1, 1963, No. 30629/63. Heading F2V. An hydraulic flow control valve, Figs. 11, 15, 16 (not shown), comprises a body 12<SP>1</SP> having a bore 14<SP>1</SP> in which a valve spool 16<SP>1</SP> is slidably positioned to control the flow of pressure fluid supplied through an inlet passage 26<SP>1</SP> to a first port branch 34b<SP>1</SP> and a second port branch 34a<SP>1</SP> leading through a throttle valve assembly 44<SP>1</SP> to either side of a double-acting hydraulic motor, and a by-pass valve 78<SP>1</SP> subjected to the pressure differential between the inlet pressure communicated to an inlet chamber 70<SP>1</SP> and the pressure in the first and second port branches 34a<SP>1</SP>, 34b<SP>1</SP> communicated to a control chamber 76<SP>1</SP>. In the neutral position with the intermediate land 98<SP>1</SP> of the valve spool 16<SP>1</SP> closing communication between the inlet passage 26<SP>1</SP> and either of the port branches 34a<SP>1</SP>, 34b<SP>1</SP> the throttle valve assembly 44<SP>1</SP> is closed, the motor remains stationary and fluid passes from the inlet passage 26<SP>1</SP>, through the by-pass valve 78<SP>1</SP>, sump chamber 72<SP>1</SP> to sump passages 30a<SP>1</SP>, 30b<SP>1</SP>. When the valve spool is displaced to the right, a throttled supply of fluid passes from the inlet 26<SP>1</SP> to the first post branch 34b<SP>1</SP> and passes through cheek valve 38b<SP>1</SP> to the by-pass valve control chamber 76<SP>1</SP> where it is operative together with a spring 86<SP>1</SP> to oppose the opening of the bypass valve 78<SP>1</SP> by the full inlet pressure conemunicated to the chamber 70<SP>1</SP>. Thus the magnitude of the opening of the by-pass valve is determined by the degree of throttling effected by the displacement of the spool valve which is tapered at the ends of the land 98<SP>1</SP> to provide a variable throttle. The pressure in the port branch 34b<SP>1</SP> therefore builds-up, displacing a piston 62<SP>1</SP> to the right and opening a throttling plunger 54b<SP>1</SP> of the throttle valve assembly 44<SP>1</SP> to thereby supply pressure fluid to the underside of the motor. A reduced diameter portion of a rod 64a<SP>1</SP> carried by the piston 62<SP>1</SP> is projected through a rod hole 110a<SP>1</SP> in a second throttling plunger 54a<SP>1</SP> to open a spring-loaded throttling pilot plunger 50a<SP>1</SP> slidable in the plunger 54a<SP>1</SP> to thereby allow fluid to exhaust from above the motor through holes 108a<SP>1</SP>, rod hole 110a<SP>1</SP>, port passage 34a<SP>1</SP> and sump passage 30a<SP>1</SP>. The throttling effect of the holes 108a<SP>1</SP>, 110a<SP>1</SP>, results in a lower pressure behind the plunger 54a<SP>1</SP> than in a working port 40a<SP>1</SP> which communicates with the fluid motor, so that fluid in the port 40a<SP>1</SP> causes the throttling plunger 54a<SP>1</SP> to open and allow an increased exhaust flow. Movement of the motor in the reverse direction is effected by displacement of the spool to the left, the operation being otherwise very similar. The embodiment of Figs. 1-9 (not shown), discloses a similar flow control valve having only one throttling plunger and associated with a single-acting gravity return hydraulic motor.